The aptly named tower mustard is a widespread North American native plant.

Identification: I first noticed these in the late summer—tall,
rigid clusters of dead sticks, lacking flowers or seeds or leaves. The “sticks” are actually seedpods.
Tower mustard begins with a rosette of gray leaves, and in the second year, it produces a flowering
stalk up to about 3½' (1 m) high. A few nondescript leaves alternate along the stalk, which
may branch at the top into slender shoots. Small, four-petaled, cream-colored flowers, each about
¼" (6.3 mm) in size, cover some of the shoots. The shoots are siliques, narrow,
rounded seedpods that look more like stems than seedpods.